Method for driving optical deflecting device array, optical deflecting device array, optical deflecting device, and image projection displaying apparatus

ABSTRACT

A method for driving an optical deflecting device array is disclosed, including in a series of processes for the light deflection operation, at least, a state of a first stage writing and recording data for indicating an inclination direction of the plate member to incline in a first inclination direction or a second inclination direction, into a semiconductor memory device arranged immediately under or adjacent to each of the plurality of optical deflecting devices; a state of a second stage switching the inclination direction of the plate member of the arbitrary optical deflecting device to the first inclination direction based on an indication of the data, and deflecting light; and a state of a third stage switching the inclination direction of the plate member of the arbitrary optical deflecting device to the second inclination direction based on the indication of the data, and deflecting light.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method for driving anoptical deflecting device capable of changing a direction an outputlight with respect to an input light, and for example, relates to atechnology suitable for an image forming apparatus such as a printer, acopier, or a like applying of an electrophotographic method, and aprojection type image video displaying apparatus such as a projector, adigital theater, or a like.

2. Description of the Related Art

For example, L. J. Hornbeck proposed a digital micromirror device of atorsion beam hinge (see “Proc. SPIE Vol. 1150, pp. 86-102 (1989)”).Moreover, a space light modulator having a micromirror group, in which atechnology of the digital micromirror device has been developed, iscalled a DMD (Digital Micromirror Device), and used in an imageprojection apparatus (for example, see “Proc. of the IEEE, vol. 86, No.8, pp. 1687-1704 (1998)”).

These devices are supported by torsion beams in which a mirror isgenerally called a hinge. By using the hinge, a reflection area can bereduced. On the other hand, in the described-above DMD, a reflectionmember is provided to a surface in addition to a hinge portion, and atwo-step structure. Moreover, although a voltage to actually drivebecomes dozens of volts by using the hinge, in order to control with 5Vthrough 7.5V as data for switching an inclination direction, aninclination switch is conducted by combining a bias voltage being dozensof volts being simultaneously applied to a plurality of pixels andrestoration force of a special spring member.

Moreover, as described in Proc. SPIE Vol. 1150, pp. 86-102 (1989), adriving method for changing an electronic potential of a mirror isdisclosed. Compared with a monostable operation, a bidirectionaloperation of a mirror having a larger deflection angle is advantageous.In order to acquire a bistability, a hinge being rigidly connected to amirror is used. The above-described driving method proposes a method forchanging a voltage of an electrode facing to the mirror simultaneouslywith a voltage of the mirror.

In addition, the applicant of the present invention previously proposedthe following optical deflecting device. That is, Japanese Laid-openPatent Application No. 2004-78136 discloses an optical deflecting devicefor changing an electrostatic attraction corresponding to an electricpotential being applied to a member having a light reflection area, andchanging a reflection direction of an incoming light flux and deflectingthe incoming light flux entering the light reflection area, the opticaldeflecting device including a substrate; a plurality of controlledmembers; a fulcrum member; and a plate member 107 a, wherein each of theplurality of control members has a stopper at an upper portion, and theplurality of control members are respectively arranged at a plurality ofedges of the substrate; the fulcrum member includes an apex configuredby a conductive member, and is arranged on an upper surface of thesubstrate; the plate member does not have a fixed end, but has the lightreflection area on an upper surface of the plate member, has aconductive layer formed by a member partially being conductive at least,is configured by a member having a conductive contact point at leastcontacted to the apex of a rear surface of the plate member, is movablyarranged in a space formed by the substrate, the fulcrum member, and thestopper, and wherein an electric potential of the plate member isapplied by a contact with the fulcrum member, an arbitrary electricpotential is applied to each of the plurality of electrodes so that amaximum electric potential difference becomes greater than apredetermined voltage, and an electric potential applied to the apex isset to be equal to either one of a maximum value and a minimum valuewhich are applied to the plurality of the electrodes.

A spatial light modulator or an optical deflecting device using theabove-described hinge has restoration force due to stiffness, and adrive voltage becomes up to dozens of volts. On the other hand, highprecision is desired for a high definition television set, a highresolution television set, and a like. In a case of increasing thenumber of pixels, a chip size becomes larger, a process flow becomesspecialized, and a material cost is increased. Accordingly, it isrequired to minimize the size of a mirror forming a pixel. Consequently,a stiffness of the hinge suspending the mirror becomes greater, and thedrive voltage is increased. Moreover, in a case of minimizing the sizeof the mirror, it is not easy to reduce the stiffness due to alimitation of precision of a micro process to thin down the hinge. Evenif its usage is not required to be minimized, the hinge is bent down ina case of reducing the stiffness and the drive voltage. As a result, acenter position of the mirror cannot be maintained. Also, in a case ofusing the hinge, the hinge is formed on a surface of the mirror. Then,an area for reflecting light is reduced.

Accordingly, a reflective surface is formed on a driving electrode, anda double structure is formed. This configuration increases thereflection area and becomes complicated. Therefore, in a case of aconfiguration using the hinge, minimizing causes that a deviceconfiguration becomes complicated and manufacturing costs increase.

Moreover, as a method for conducting a bistable operation using a hinge,Japanese Laid-open Patent Application No. 5-150173 discloses a methodfor switching an inclination of a mirror by cooperatively actuating afirst electric potential of the mirror and an electric potential of anelectrode. A beam is a torsion beam, and the restoration force of thestiffness of the hinge is mandatory to be used. There is a problem thatthe mirror as a beam cannot rotate without a torque. In a case in thatan inclination direction of the mirror is changed, when a switch signalis input to either one of two-way directions, a direction is similarlychanged. However, in order to switch an inclination direction by anelectric potential of approximately 5V that is generally an operationvoltage of an LSI (Large Scale Integration), since there is an unstablestate due to a balance between a stiff restoration force and anelectrostatic force, a switch of the inclination direction is limited toa narrow range of the driving voltage. Furthermore, it is difficult tocombine with the LSI which operates at approximately 3.3V as the drivingvoltage. Also, there is another problem in that the beam immediatelyoperates when data are written. This occurs since a display period isinfluenced if a data write is delayed. In addition, in the configurationusing the hinge, an inclination is made based on one axis alone by usingthe hinge. As a result, an light deflection is made based on one-axisdirection alone.

On the other hand, in the optical deflecting device (disclosed inJapanese Laid-open Patent Application No. 2004-78136), a plate memberhaving a light reflection area does not have a fixed end such as a hingeor a hinge being less rigid is used, it is possible to easily conduct abistable switch. Electrodes electrically contacted to a conductive layerof the plate member and electrodes facing to the plate member aredivided into two groups with respect to a fulcrum member, an arbitraryelectric potential is applied to each of electrode groups, and anelectric potential of the electrodes electrically contacted to theconductive layer of the plate member is switched. Accordingly, it ispossible to easily switch an inclination direction of the plate member.

Moreover, in a configuration in which the plate member does not have afixed member such as a torsion beam, the inclination direction of theplate member can be changed based on two axes by a configuration of theelectric potential being applied to a plurality of electrodes. Sincestiffness of the torsion beam is not used, further precision can beeasily realized.

However, even in a case in that a control electric potential applied toeach of the electrode groups is a direct driving voltage and an LSImemory is used, if a response time of the plate member is less than 5μsec., a voltage of more than 10V is required. In a case of configuringan image displaying apparatus by combining with the LSI memory, adedicated driving device of a higher voltage is required.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide a method fordriving an optical deflecting device array capable of controlling aninclination direction of a plate member with a low voltage generallyrequired as an operation voltage of an LSI memory circuit, an opticaldeflecting device array, an optical deflecting device, and an imageprojection displaying apparatus, in which the above-mentioned problemsare eliminated.

A more specific object of the present invention is to provide a methodfor driving an optical deflecting device array, which arranges aplurality of optical deflecting devices in one dimension or in twodimensions, each of the plurality of optical deflecting devices in whicha plate member having a light reflection area rotates on a rotation axisor a fulcrum being as a center, and a light deflection operation isconducted by changing a reflection direction of an incoming light fluxin that the plate member includes a conductive layer, an electrode iscontacted or fixed to the conductive layer to apply an electricpotential, and each of the plurality of optical deflecting deviceincludes an electrode group including a plurality of electrodes arrangedto face to the plate member, and switching an inclination direction ofthe plate member due to an electrostatic attraction caused by anelectric potential difference between an arbitrary electrode in theelectrode group and the electrode applying the electric potential to theconductive layer, said method including: in a series of processes forthe light deflection operation, at least, a state of a first stagewriting and recording data for indicating an inclination direction ofthe plate member to incline in a first inclination direction or a secondinclination direction, into a semiconductor memory device arrangedimmediately under or adjacent to each of the plurality of opticaldeflecting devices; a state of a second stage switching the inclinationdirection of the plate member of the arbitrary optical deflecting deviceto the first inclination direction based on an indication of the data,and deflecting light; and a state of a third stage switching theinclination direction of the plate member of the arbitrary opticaldeflecting device to the second inclination direction based on theindication of the data, and deflecting light.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the present invention will be describedwith reference to the accompanying drawings.

FIG. 1 is a diagram showing a configuration according to an embodimentof the present invention;

FIG. 2 is a diagram showing an example of arranging optical deflectingdevices according to the present invention in a two-dimensional array;

FIG. 3 is a first variation of the first embodiment of the presentinvention;

FIG. 4 is a second variation of the first embodiment of the presentinvention;

FIG. 5 is a diagram for explaining an operation according to the firstembodiment of the present invention;

FIG. 6 is a diagram for explaining the operation according to the firstembodiment of the present invention;

FIG. 7 is a diagram for explaining the operation according to the firstembodiment of the present invention;

FIG. 8 is a diagram for explaining a variation of the operationaccording to the first embodiment of the present invention;

FIG. 9 is a diagram for explaining the variation of the operationaccording to the first embodiment of the present invention;

FIG. 10 is a diagram for explaining the variation of the operationaccording to the first embodiment of the present invention;

FIG. 11 is a diagram showing a timing chart according to the firstembodiment of the present invention;

FIG. 12 is a diagram showing a configuration example of maintaining anelectric potential of a plate member according to the first embodimentof the present invention;

FIG. 13 is a diagram showing a configuration according to a secondembodiment of the present invention;

FIG. 14 is a diagram showing a variation of the second embodiment of thepresent invention;

FIG. 15 is a diagram for explaining an optical deflection operationaccording to the second embodiment of the present invention;

FIG. 16 is a diagram for explaining the optical deflection operationaccording to the second embodiment of the present invention;

FIG. 17 is a diagram for explaining operations in a state 1 through astate 2 according to the second embodiment of the present invention;

FIG. 18 is a diagram for explaining the operations in the state 1through the state 2 according to the second embodiment of the presentinvention;

FIG. 19 is a diagram for explaining the operations in the state 1through the state 2 according to the second embodiment of the presentinvention;

FIG. 20 is a diagram for explaining the operations in the state 1through the state 2 according to the second embodiment of the presentinvention;

FIG. 21 is a diagram for explaining the operations in the state 1through the state 2 according to the second embodiment of the presentinvention;

FIG. 22 is a diagram for explaining the operations in the state 1through the state 2 according to the second embodiment of the presentinvention;

FIG. 23 is a diagram for explaining the operations in the state 1through the state 2 according to the second embodiment of the presentinvention;

FIG. 24 is a diagram showing a timing chart according to the secondembodiment of the present invention;

FIG. 25 is a diagram showing a configuration according to a thirdembodiment of the present invention;

FIG. 26 is a diagram showing a configuration according to a fourthembodiment of the present invention; and

FIG. 27 is a diagram showing a configuration according to a fifthembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following, an embodiment of the present invention will bedescribed with reference to the accompanying drawings.

In a conventional method for driving an optical deflecting device array,in order to rotate a plate member and switch an inclination direction, alow voltage is required. However, in a method for driving an opticaldeflecting device array according to the present invention, it ispossible to control the inclination direction of the plate member with alow voltage generally required as an operation voltage of the LSI memorycircuit.

A principal of the present invention will be described as follows. Theplate member having a reflection area is inclined with respect to afulcrum member. A plurality of electrodes facing toward the plate memberare divided into two groups with respect to the fulcrum member. Forexample, a low electric potential of a regular output of an LSIsemiconductor memory device is applied to a first electrode group, whichis at a side where the plate member inclines. A high electric potentialof a conductive layer of the plate member is applied to the conductivelayer of the plate member. A high electric potential within a range tosufficiently rotate the plate member is applied to a second electrodegroup which has a wider space for the plate member.

However, since the plate member is distanced from the electrodes, anelectrostatic force becomes weak. An electric potential difference ofthe electrostatic force between the first electrode group at the sidewhere the plate member inclines and the plate member, but theelectrostatic force is strong since the first electrode group is closerto the plate member. Thus, a longer interval of the electric potentialwithin a range in which a rotation is not occurred is set to the secondelectrode group which electrodes are distance from the plate member. Ina case in that the electric potential of the conductive layer of theplate member is the low electric potential of the LSI, the electricpotential difference becomes 0V between the first electrode group at theside where the plate member inclines the conductive layer of the platemember, and the electrostatic force does not work. In this case, sincethe electrostatic force is greater between the plate member and thesecond electrode group at a side of the longer interval of the electricpotential, the plate member can be inclined in a direction to which theelectrostatic force is greater.

As described above, even in a case of a low voltage such as the electricpotential of the LSI semiconductor memory device, it is possible todrive and control an inclination of the plate member with a highvoltage. The greater the electric potential difference between the platemember and the electrodes, the shorter a response time of an inclinationdisplacement. Accordingly, it is possible to drive the inclination ofthe plate member at higher speed. Moreover, it is possible to furtherdecrease the voltage to be lower than 3.3V. It is possible to minimize asemiconductor memory device such as the LSI combined with the opticaldeflecting device. It is possible to further minimize the shape of theplate member. It is possible to integrate an optical deflecting devicearray with a higher density.

In the method for driving the optical deflecting device using theabove-described mechanism according to the present invention, there arethe following three states. First, in the present invention, the platemember inclines in an OFF inclination direction when light is OFF, andthe plate member inclines in an ON inclination direction when light isON.

(1) in a display period in that as a pixel for forming an image, theplate member is maintained in the ON inclination direction or the OFFinclination direction during an indicated period, data determining ON orOFF are written and recorded.

(2) the plate member is inclined in the OFF inclination direction whenOFF is indicated, or the plate member is maintained to be in the ONinclination direction when ON is indicated.

(3) the plate member is inclined in the ON inclination direction inresponse to an ON signal. In a case in that OFF is indicated, aninclination direction is not changed, and OFF is maintained.

And, goes back to the above (1), and the inclination direction ismaintained and the image is displayed.

For example, if the method for driving the optical deflecting devicearray according to the present invention is applied to a method fordisplaying a gradation of the pixel in a time length of ON or OFF, it ispossible to express an image by using a state 1 as a periodcorresponding to the gradation.

As described above, in the present invention, it is possible to overcomethe problem in which it is difficult to minimize the size of the opticaldeflecting device using the hinge, by operating the plate member whichdoes not have a fixed portion, in accordance with the method for drivingthe optical deflecting device array. In addition, the plate member whichdoes not have the fixed portion can be inclined based on one of twoaxes, and light entering from two directions can be output by switchingto one direction. Accordingly, it is possible to form the opticaldeflecting device capable of switching light to select one of twocolors, and outputting the light.

In the method for driving the optical deflecting device according to thepresent invention, even in a two-axis deflection, it is possible tocontrol the inclination direction of the plate member at the lowvoltage, which is approximately 5V of data output in a regularsemiconductor memory device such as the LSI, and it is possible tosimultaneously switch a display with a plurality of pixels. If thepresent invention is used for a projector, it is possible to overcome aproblem of color breaking that occurs in a single-plate opticaldeflecting device since a color switch is conducted for each of theplurality of pixels.

First Embodiment

FIG. 1A and FIG. 1B are diagrams showing a configuration according to afirst embodiment of the present invention. Electrode groups 103 a and103 c including a plurality of electrodes are arranged on a substrate101 through an insulation film 102, and the electrodes are covered withan insulation film. Moreover, a plate member 107 a having a lightreflection area of a conductive layer 107 b of the plate member 107 aare mounted on a fulcrum member 106. A conductor is exposed at an apexof an electrode of the fulcrum member 106, and the apex is electricallycontacted to a conductive layer of the plate member 107 a. Accordingly,it is possible to apply the electric potential to the conductive layer107 b of the plate member 107 a from the electrode of the fulcrum member106.

The plate member 107 a can conduct a certain amount of a rotation(inclination), and each control member 108 suppresses a movement so thatthe plate member 107 a does not jump out. An inclination angle of theplate member 107 a is an angle obtained by calculating an arcsine of ½of a length of the plate member 107 a and a height of the fulcrum member106 adjacent to the plate member 107 a.

The plate member 107 a is displaced to incline to either one of anelectrode a or an electrode c as a result of comparing an electrostaticforce by the conductive layer 107 b and the electrode group 103 a(electrode a) with another electrostatic force by the conductive layer107 b and the electrode group 103 c (electrode c). Moreover, even if theconductive layer 107 b of the plate member 107 a is temporarilydistanced from an electrode electrically connected on the substrate 101,the conductive layer 107 b of the plate member 107 a holds an electriccharge, and an equivalent electrostatic force works. All theelectrostatic force are not out of force. In addition, since theelectrostatic force works, it is possible for the plate member 107 a tocontact to an electrode side again.

As shown in FIG. 2, a plurality of the optical deflecting devicesaccording to the present invention can be arranged in a two dimensionalarray, and can be used, for example, as a light bulb of a displayingapparatus such as a projector.

FIG. 3 is a diagram showing a configuration example of the opticaldeflecting device in that the plate member 107 a and the conductivelayer 107 b are partially used as a torsion beam hinge 109, and theplate member 107 a is suspended by the torsion beam hinge 109. In thisconfiguration example, since stiffness of the torsion beam hinge 109,and the torsion beam hinge 109 is dangled, the torsion beam hinge 109 issupported by the fulcrum member 106. In a case in that the stiffness ofthe torsion beam hinge 109 is weak and a voltage is not applied to theelectrodes, the plate member 107 a and the conductive layer 107 b areinclined.

As described as Japanese Laid-open Patent Application No. 2004-78136,the optical deflecting device according to the present invention can befabricated based on a semiconductor fabricating process. Preferably, onthe same substrate 101, active element groups for a drive are arrangedon a lower layer, and the electrode groups including the plurality ofelectrodes and the plate member 107 a are multiply layered.Alternatively, a substrate of the active element groups and a substrateforming the electrode groups and the plate member 107 a can be bondedtogether.

In the first embodiment, the plate member 107 a is formed by aconductive member, and the electric potential of the conductive layer107 b of the plate member 107 a is defined as the electric potential ofthe plate member 107 a. In a case in that the plate member 107 a isconfigured by an insulation layer and a conductive layer, the electricpotential of the conductive layer of the plate member 107 a is definedas the electric potential of the plate member 107 a.

An operation principal in the method for driving the optical deflectingdevice array according to the present invention will be described. Theplate member 107 a is not fixed by fixing members such as torsion beams,and does not have a restoration force due to stiffness. Alternatively,the plate member 107 a is suspended by the torsion beam having weakstiffness. The plate member 107 a is inclined by the fulcrum member 106.A distance between the plate member 107 a and the electrodes at the sidewhere the plate member 107 a inclines is much shorter than a distancebetween the plate member 107 a and the electrodes at an opposite side.The electrode groups are classified into an electrode group far from theplate member 107 a and an electrode group closer to the plate member 107a.

Since the electrostatic force is in inverse proportion to a square of adistance, even if a predetermined low voltage is applied between theplate member 107 a and the electrodes at the side where the plate member107 a inclines, the plate member 107 a can be pulled by theelectrostatic force. Overwhelming this electrostatic force, anotherelectrostatic force working between the plate member 107 a and theelectrodes at the opposite side with respect to the fulcrum member 106can be set not to be greater since the distance between the plate member107 a and the electrodes at the opposite side. That is, even if theelectric potential difference is smaller in the electrostatic forcebetween the plate member 107 a and the electrodes having the shortestaverage distance, the electrostatic force can be greater than anotherelectrostatic force between the plate member 107 a and the electrodeshaving a longer distance to the plate member 107 a. For example, in acase in that the inclination angle is 10°, when the same electricpotential difference is applied to close electrodes to the plate member107 a and far electrodes from the plate member 107 a, the electrostaticforce working at the close electrodes is approximately dozen times toseveral hundred times greater than the far electrodes.

Compared by using voltage, since the electrostatic force is inproportion to a square of voltage, a difference of the electrostaticforces working at the close electrodes and the far electrodes becomesseveral times or dozen times. For example, if it is assumed to be 10times, for example, the electrostatic force in a case of applying 5V tothe plate member 107 a and the close electrodes is approximately equalto the electrostatic force in a case of applying 50V to the plate member107 a and the far electrodes. If 5V is applied to the plate member 107a, 0V is applied to the electrode a when the plate member 107 a inclinesto a side of the electrode a, and 20V is applied to the electrode c, theelectrostatic force between the electrode a and the plate member 107 ais greater than the electrostatic force between the electrode c and theplate member 107 a. This method for driving the optical deflectingdevice can be used for a spatial light modulator having a mirror using atorsion beam. In addition, even if stiffness of the torsion beam isrelatively weak, an operation can be conducted.

FIG. 4 is a diagram showing a variation of the first embodiment of thepresent invention. In FIG. 4, the electrodes 103 a and 103 c facing to aplate member 107 a are inclined with respect to the substrate 101. Bymaking the electrodes 103 a and 103 c closer to the plate member 107 a,it is possible to increase the electrostatic force. Accordingly, forexample, a ratio of the electrostatic force between the plate member 107a and the electrode 103 a at an inclination side where the plate member107 a inclines to the electrostatic force between the plate member 107 aand the electrode 103 c at the far side distanced from the plate member107 a can be improved to be several hundred times, for example, 400times. A voltage ratio can be improved to be a few dozen times, forexample, 20 times.

By this configuration, in a case of applying 3.3V between the platemember 107 a and the electrode 103 a closer to the plate member 107 a,even if a voltage up to 66V is applied between the plate member 107 aand the electrode 103 c far from the plate member 107 a, the platemember 107 a does not change the inclination direction. The method fordriving the optical deflecting device array according to the presentinvention can be used in a case in that the operation voltage is 3.3Vfor a high density LSI including the semiconductor memory device. Sincethe operation voltage of a highly integrated LSI is lower, if thedriving voltage is lower, an optical deflecting device including astorage device such as SRAM (Static Random Access Memory) can beminimized.

In the following, a method for controlling the plate member 107 a byusing the semiconductor memory such as the LSI in the above-describedconfiguration will be described. The LSI is combined to control theplate member 107 a. In general, the operation voltage for the LSI is 5V.In the following, VH denotes a high value (high electric potential) of asignal voltage of the LSI, and for example, is illustrated as 5V.However, the present invention is not limited to a voltage of 5V, andthe same method can be used in a case of 3.3V or 2V. In general, a lowelectric potential VL is 0V. Thus, a case of VH=5V, VL=0V, and E=20Vwill be illustrated.

In light deflection, a light OFF state is defined as a case in that theplate member 107 a inclines to the side of the electrode a, and a lightON state is defined as a case in that the plate member 107 a inclines tothe side of the electrode c and light is reflected in a predetermineddirection.

The electrode a and the electrode c are symmetrically arranged and havethe same size of an area. For example, when the plate member 107 ainclines to the side of the electrode a, it shows approximately 50 asthe ratio of the electrostatic force between the plate member 107 a andthe electrode a to which the plate member 107 a inclines to theelectrostatic force between the plate member 107 a and the electrode cdistanced from the plate member 107 a. Since force is proportional to asquare of a voltage, a voltage ratio is a square root of the force.Thus, the voltage ratio of the electrostatic force becomes 7.0 times.Since the high electric potential VH is 5V, when the electric potentialdifference is 5V between the electrode a and the plate member 107 a, theplate member 107 a maintains inclining to the side of the electrode auntil the electric potential difference is approximate 35V between theplate member 107 a and the electrode c. Thus, the voltage can be useduntil 35V, but 30V is defined as an electric potential E.

Next, the method for driving the optical deflecting device arrayaccording to the present invention will be broadly described. A firstinclination direction is defined in a case in that the plate member 107a inclines to the side of the electrode a, light is turned OFF, and astate becomes an OFF state. A second inclination is defined in a case inthat the plate member 107 a inclines to the side of the electrode c,light is turned ON when the light is reflected and output at the platemember 107 a, and the state becomes an ON state.

A state 1 is a period for a display. Also, the state 1 is a state ofwriting and recording data for indicating the inclination direction ofthe plate member 107 a. However, the inclination direction for thedisplay is maintained.

A state 2 (OFF execution) is a state in that the plate member 107 a isinclined in the first inclination direction in accordance with OFFinformation written and recorded in the state 1, and the state 2 showsan OFF state. In a case in that the plate member 107 a has been alreadyturned OFF, the state 2 remains as it is. On the other hand, in a casein that the plate member 107 a is indicated to be ON, the inclinationdirection of the plate member 107 a is not changed, and the state 2remains as the ON state.

A state 3 (ON execution) is a state in that the plate member 107 a isinclined in the second inclination direction in accordance with ONinformation written and recorded in the state 1, and the state 2 showsthe ON state. In a case in that the plate member 107 a has been alreadyturned ON, the state 3 remains as it is. On the other hand, in a case inthat the plate member 107 a is indicated to be OFF, since the platemember 107 a has been already turned OFF, the state is maintained.

The state becomes the state 1 again. Data are displayed, and dataindicating the inclination direction are written and recorded. Thisstate transition is conducted for the entire or a part of opticaldeflecting devices forming the optical deflecting device array, all atonce.

A case example will be described to use the method for driving theoptical deflecting device array according to the present invention in acase of conducting a gradation display based on a time length of ON orOFF in the state 1. However, the present invention is not limited to useit for this gradation display. For example, such as a maximum displayperiod, half the maximum display period, one quarter the maximum displayperiod, one eighth the maximum display period, and a like, bits areformed by reducing by half, and gradation can be displayed by combiningbits of these periods. Eight bits are used for 256 gradations. In thiscase, when three colors are depicted by using a single opticaldeflecting device using a color wheel, for example, a minimum displayperiod is approximately 20 μsec.

Advantageously, in the method for driving the optical deflecting devicearray according to the present invention, by data written in the state1, it is possible to switch between an OFF display and ON display withrespect to multiple pixels simultaneously in the state 2 and the state3. The state 2 and the state 3 can be a few μsec., and the statetransition is sufficiently fast, so that human eyes cannot recognize thestate transition. As described above, since the plate member 107 a doesnot switch the inclination direction while data are being written, thereis no time lag caused by ON or OFF pixels. Also, there is no influenceto the minimum display period.

Next, an operation of the electric potential of each electrode will bedescribed for each state. FIG. 5, FIG. 6, and FIG. 7 are diagramsshowing the electric potential and an inclination state of the platemember 107 a, and for explaining the operation of the electric potentialof each electrode. The first inclination direction is defined to theside of the electrode a, and an electrode arranged in the firstinclination direction is defined as the electrode a. The secondinclination direction is defined to the side of the electrode c, and anelectrode arranged in the second inclination direction is defined as theelectrode c.

Each electric potential of the electrode a and the electrode c is set asdescribed as follows. However, in a case of applying to the opticaldeflecting device array, it is preferable to simultaneously change theelectric potentials for each of the plurality of the optical deflectingdevices forming the optical deflecting device array.

In accordance with a condition 1, the electric potentials to apply tothe plate member 107 a are defined as V1=VL=0V, and V2=VH.

State 1 (FIG. 5) (0V is applied to the plate member 107 a when the ONinformation is written, and VH is applied to the plate member 107 a whenthe OFF information is written):

First, it is assumed that the plate member 107 a inclines to the side ofthe electrode a. The electric potential E (E<VL or E>VH+α, α is requiredto be greater than the electric potential in which the electrostaticforce between the plate member 107 a and the electrode a becomes greaterthan the electrostatic force between the plate member 107 a and theelectrode c) is applied to the electrode a, the electric potential E isapplied to the electrode c, and 0V or VH is applied to the plate member107 a. An electric potential difference is E or E−VH between the platemember 107 a and the electrode a. In addition, since a distance isshorter, the electrostatic force at the side of the electrode a isstronger than the side of the electrode c, and the plate member 107 aremains to incline at the side of the electrode a, regardless of theelectric potential 0V or VH.

(1-a) the plate member 107 a inclines to the first inclinationdirection.

At an electric potential V3=E which is applied to the electrode a, withrespect to both an electric potential V1=0V as a low electric potentialof the plate member 107 a and an electric potential V2=5V as a highelectric potential, the electrostatic force works due to an electricpotential difference V3−V1=E or V3−V2=E−VH, and an inclination of theplate member 107 a is maintained.

(1-b) the plate member 107 a inclines in the second inclinationdirection.

At an electric potential V4=E which is applied to the electrode c, withrespect to both the electric potential V1=0V as the low electricpotential of the plate member 107 a and the electric potential V2=5V asthe high electric potential, the electrostatic force works due to anelectric potential difference V4−V1=E or V4−V2=E−VH, and an inclinationof the plate member 107 a is maintained.

State 2 (FIG. 6) (the OFF information is executed. (2-a) and (2-b) showthe plate member 107 a in a case in that the ON information is writtenin the state 1, and (2-c) and (2-d) show the plate member 107 a in acase in that the OFF information is written in the state 1.):

The electric potential of the electrode a is V3, and the electricpotential of the electrode c is V4=V2 (condition 2).

(2-a) when the plate member 107 a inclines in the first inclinationdirection, the electric potential V3=E is applied to the electrode a,and the electric potential V4=VH is applied to the electrode c, theelectric potential of the plate member 107 a is V1=0V, the electricpotential difference between the plate member 107 a and the electrode ais E and the electrostatic force thereof is F1, and the electricpotential difference between the plate member 107 a and the electrode cis VH and the electrostatic force thereof is F2. The electric potentialdifference E is significantly greater than the electric potentialdifference VH. The plate member 107 a is closer to the electrode a, andthe plate member 107 a is farther from the electrode c. Since F1>F2, theplate member 107 a maintains inclining in the first inclinationdirection.

(2-b) the plate member 107 a inclines in the second inclinationdirection, the plate member 107 a is farther from the electrode a, andthe plate member 107 a is closer to the electrode c. The electricpotential of the plate member 107 a is V1=0V. The electric potentialdifference between the plate member 107 a and the electrode a is E.However, since the plate member 107 a is farther from the electrode a,the electrostatic force F1 becomes weaker. On the other hand, the platemember 107 a is closer to the electrode c, and the electric potentialdifference is VH. However, the electrostatic force F2 can be greater. Itis possible to set the electric potential difference E where F1<F2, andthe plate member 107 a maintains inclining in the second inclinationdirection.

(2-c) the plate member 107 a inclines in the first inclinationdirection, the electric potential of the plate member 107 a is V2=VH,and the electrostatic force F3 due to the electric potential differenceE−VH between V3 and V2 becomes greater while the plate member 107 abecomes closer to the electrode a. The electric potential differencebetween V4 and V2 is 0V and the electrostatic force F4=0 does not work.Since F3>F4, the plate member 107 a inclines in the first inclinationdirection.

(2-d) the plate member 107 a inclines in the second inclinationdirection, the electric potential difference between V3 and V2 is E−VH,and the electrostatic force F3 occurs. The electric potential differencebetween V4 and V2 is 0V, and F4=0. Since F3>F4, the inclinationdirection of the plate member 107 a switches from the second inclinationdirection to the first inclination direction.

State 3 (FIG. 7) (the ON information is executed. (3-a) and (3-b) showthe plate member 107 a in a case in that the ON information is writtenin the state 1, and (3-c) and (3-d) show the plate member 107 a in acase in that the OFF information is written in the state 1.): in thiscase, the electric potential of the electrode a is V5=V1=0V (condition2), and the electric potential of the electrode c is V6=E.

(3-a) the plate member 107 a inclines in the first inclinationdirection. The electric potential of the plate member 107 a is V1=0V,and the electric potential difference between V5 and V1 is 0V. Theelectrostatic force between the plate member 107 a and the electrode ais F5=0, and the electrostatic force F6 occurs due to the electricpotential difference E between V6 and V1. Since F5<F6, the inclinationdirection of the plate member 107 a switches from the first inclinationdirection to the second inclination direction.

(3-b) the plate member 107 a inclines in the second inclinationdirection. The electric potential of the plate member 107 a is V1=0V,and the electric potential difference between V5 and V1 is 0V. Theelectrostatic force between the plate member 107 a and the electrode ais F5=0, the electrostatic force F6 occurs due to the electric potentialbetween V6 and V1, and the plate member 107 a maintains inclining in thesecond inclination direction.

(3-c) the plate member 107 a inclines in the first inclinationdirection. The electric potential of the plate member 107 a is V2=VH,the electric potential difference between V5 and V1 is VH. Theelectrostatic force F7 works between the plate member 107 a and theelectrode a. The electric potential difference between V6 and V2 isE−VH, and the electrostatic force F8 becomes smaller between the platemember 107 a and the electrode c since the plate member 107 a becomesfarther from the electrode c. It is possible to set F7>F8, and the platemember 107 a maintains inclining in the first inclination direction.

(3-d) the plate member 107 a inclines in the second inclinationdirection. The electric potential of the plate member 107 a is V2=VH,and the electric potential difference between V5 and V1 is VH. Inaddition, the plate member 107 a is far from the electrode a, and theelectrostatic force F7 is small. The electric potential differencebetween V6 and V2 is E−VH, and the electrostatic force F8 between theplate member 107 a and the electrode c becomes greater since the platemember 107 a becomes farther from the electrode c. It is possible to setF7>F8, and the plate member 107 a maintains inclining in the secondinclination direction.

FIG. 8, FIG. 9, and FIG. 10 are diagrams showing a variation accordingto the present invention. As shown in FIG. 8, in the state 1, by settingthe electric potential of the electrode a to be lower than VL=0V such as−E, the electrostatic force is caused to the plate member 107 a by anelectrostatic induction with E of the electrode c, so that the platemember 107 a can be gravitated to a substrate side. By thisconfiguration, it is possible for the plate member 107 a to furtherstably maintain a state against disturbance such as vibration. In thestate 2 (FIG. 9), E is set to be E+VH, so that the same electrostaticforce of the state 3 in FIG. 7 can be used.

FIG. 11 is a timing flowchart for transiting from the state 1 to thestates 2, 3, and 1. In FIG. 11, light is OFF when the plate member 107 ainclines to the side of the electrode a, and the light is ON when theplate member 107 a inclines to the side of the electrode c. In FIG. 11,“ON” and “OFF” indicate the inclination direction of the plate member107 a corresponding to a light ON and a light OFF, respectively. Alateral axis shows time. A longitudinal axis shows electric potentialsof electrodes. From a top in FIG. 11, a voltage change of the electrodea in a time sequence, an electric potential change applied to the platemember 107 a due to the fulcrum member 106 being conductive in the timesequence, and a voltage change of the electrode c in a time sequence areshown.

Since the electric potential of the plate member 107 a changes to be 0Vor VH based on data, a timing of writing data to change the electricpotential is shown by crossed lines. In this example, the state transitsin an order of the state 1, the state 2, the state 3, and the state 1.Alternatively, the order can be of the state 1, the state 3, the state2, and the state 1. A boundary of the state is shown by a dashed line.

In the state 1, a display is conducted based on image data, and ON dataor OFF data to display in a next state 1 are written by 0V or VH,respectively. The ON data are written by applying 0V as the electricpotential of the plate member 107 a ((1-b) in FIG. 5). The OFF data arewritten by applying VH as the electric potential of the plate member 107a ((1-a) in FIG. 5).

In the state 2, in accordance with an indication of the OFF data writtenin the state 1, the plate member 107 a is inclined to an OFF side ((2-d)in FIG. 6). In a case in that the OFF data are indicated in the state 1but the plate member 107 a has been already inclined at the OFF side,the state is maintained as it is ((2-c) in FIG. 6). In a case in thatthe ON data are indicated in the state 1, the inclination direction ismaintained ((2-a) and (2-b) in FIG. 6).

In the state 3, in accordance with in indication of the ON data writtenin the state 1, the plate member 107 a is inclined to an ON side ((3-a)in FIG. 7). In a case in that the ON data are indicated in the state 1but the plate member 107 a has been already inclined to the ON side, thestate is maintained as it is ((3-b) in FIG. 7). In a case in that theOFF data are indicated in the state 1, the inclination direction ismaintained ((3-c) and (3-d) in FIG. 7).

While maintaining the inclination direction in the state 1, data for thenext state 1 are written.

During the time length of the light ON state or the light OFF state, themethod for driving the optical deflecting device array can be used in amethod for conducting the gradation of the display. In particular, it ispreferred to arrange the optical deflecting device according to thepresent invention on a memory device as a semiconductor memory deviceformed on a substrate of a semiconductor, a ceramics such as a glass, aplastic, or a like, and connect an output of the memory device to theoptical deflecting device. A configuration example will be described inthat the electric potential of the plate member 107 a is set as anoutput electric potential level of the memory device, and becomes VH asthe high electric potential or 0V of the low electric potential. As thememory device, an SRAM, a DRAM (Dynamic Random Access Memory), a flashmemory, and a like can be used.

FIG. 12A is a diagram showing a configuration example using the SRAM. Anoutput of the SRAM is connected to the fulcrum member 106 electricallyconnected to the plate member 107 a. FIG. 12B is a diagram showing acircuit example having a function of the DRAM in which a capacitor isarranged at a gate of a transistor, and the electric potential ismaintained by charging the capacitor.

Second Embodiment

Next, a two-axis operation will be described as one of features in themethod for driving the optical deflecting device array.

FIG. 13 is a diagram for explaining a configuration and an operation ina case of the two-axis operation. In FIG. 13, electrodes 103 a through103d are arranged on a substrate 101 through an insulation film 102, andthe electrodes 103 a through 103 d are covered with another insulationfilm (not shown). In addition, the plate member 107 a is mounted on thefulcrum member 106 serving as an electrode for a conductive layer of theplate member 107 a. An apex of the electrode of the fulcrum member 106exposes a conductor, and electrically contacts to the conductive layer107 b of the plate member 107 a. Thus, it is possible to apply theelectric potential to the conductive layer 107 b of the plate member 107a from the electrode of the fulcrum member 106. The plate member 107 ais controlled by a control member 108, so that the plate member 107 adoes not jump out.

The plate member 107 a includes a light reflection area, and furtherincludes the conductive layer 107 b. A plurality of electrodes, anelectrode a, an electrode b, an electrode c, and an electrode d arearranged to face to the plate member 107 a. An electrode is electricallyconnected to the conductive layer 107 b of the plate member 107 a orestablishes an electric potential. Moreover, an electrode configurationis not limited to the above-described configuration. Alternatively, forexample, as shown in FIG. 14, an electrode arrangement and aninclination displacement of the plate member 107 a can be configured. Inany case, four electrodes are arranged at positions surrounding thefulcrum member 106. Furthermore, two electrodes adjacent to each otherare set to be the same electric potential. Therefore, it is possible toswitch an axis.

A light deflection operation will be described with reference to FIGS.15A and 15B, and FIGS. 16A and 16B. A reflective surface of the platemember 107 a is inclined by the fulcrum member 106. By inclining andentering an incoming light by an inclination angle to the plate member107 a, when the plate member 107 a inclines, the incoming light isperpendicularly reflected at the substrate 101. In a case in that theplate member 107 a inclines to an opposite side, the incoming light isnot perpendicularly reflected at the substrate 101. By using an angledifference, it is defined that light is ON when the light isperpendicularly reflected to the substrate 101 and light is OFF when thelight is reflected at a slant. Moreover, in a case of a two-axisoperation, the inclination angles of four directions are generally thesame. The incoming light inclined with respect to the plate member 107 ais emitted from two directions in which the incoming light is displacedat 90° in a substrate plane, so as to switch two types of light by usinginclination directions of the incoming light in the two directions.

In the second embodiment, the plate member 107 a has 0.1 μm thickness,10 μm square, and 12° inclination angle, and four electrodes having 4 μmsquare are used. In addition, the four electrodes a through d aresymmetrically arranged and have the same area. For example, in a case inthat the plate member 107 a inclines to sides of the electrode and theelectrode b, a ratio of the electrostatic force between the plate member107 a and the electrodes a and b to which the plate member 107 ainclines, to the electrostatic force between the plate member 107 a andthe electrodes c and d which are distanced from the plate member 107 ais approximately 100 times. Since force is proportional to a square ofthe voltage, a voltage ratio is a square root of the ratio of theelectrostatic force. Then, in this case, the voltage root is 10 times.Since VH is 5V, when 0V is applied to the electrode a and the electrodeb, and 5V is applied to the plate member 107 a, the plate member 107 adoes not move to sides of the electrode c and the electrode d even ifthe voltage is applied to the electrode c and the electrode d untilapproximately 50V. The electric potential E is available until 50V.

The method for driving the optical deflecting device array according tothe present invention can be applied not only for a configuration inwhich the plate member 107 a is not fixed, but also for a configurationin which the plate member 107 a is hung by a torsion beam or a likewhich has low stiffness and is not easily restored. In a case in thatthe stiffness and a restoration force of the torsion beam are lower, theinclination direction can be maintained at a side of a closer electrodeby the electrostatic force due to an electric potential difference of VHbetween the plate member 107 a and the closer electrode to the platemember 107 a.

FIG. 17, FIG. 18, FIG. 19, FIG. 20, FIG. 21, FIG. 22, and FIG. 23 arediagrams for explaining operations in the state 1 (display and datawrite), the state 2 (inclination direction change of the plate member107 a), and the state 3 (restore of the plate member 107 a) by using twoaxes, respectively. If E>VH and the electric potential differencebetween the plate member 107 a and two electrodes at which the platemember 107 a inclines is greater than VH, even though the electricpotential between the plate member 107 a and other two electrodes whichare distanced from the plate member 107 a is E, values of VH and E canbe set so that the plate member 107 a does not move.

State 1 (electric potentials of the electrode a, the electrode b, theelectrode c, and the electrode d are E): see FIG. 17

(1-a) when the plate member 107 a inclines to the side of the electrodea and the electrode b, the electric potentials of the electrode a andthe electrode b closer to the plate member 107 a are E, and theelectrostatic forces are greater. Accordingly, even if the electricpotential of the plate member 107 a is VH or 0V, the inclinationdirection can be maintained.

(1-b) when the plate member 107 a inclines to the side of the electrodec and the electrode d, the electric potentials of the electrode c andthe electrode d closer to the plate member 107 a are E, and theelectrostatic forces are greater. Accordingly, even if the electricpotential of the plate member 107 a is VH or 0V, the inclinationdirection can be maintained.

(1-c) when the plate member 107 a inclines to the side of the electrodeb and the electrode d, the electric potentials of the electrode b andthe electrode d closer to the plate member 107 a are E, and theelectrostatic forces are greater. Accordingly, even if the electricpotential of the plate member 107 a is VH or 0V, the inclinationdirection can be maintained.

(1-d) when the plate member 107 a inclines to the side of the electrodea and the electrode c, the electric potentials of the electrode a andthe electrode c closer to the plate member 107 a are E, and theelectrostatic forces are greater. Accordingly, even if the electricpotential of the plate member 107 a is VH or 0V, the inclinationdirection can be maintained.

State 2 (electrode a: V3=E, electrode b: V3=E, electrode c: V4=VH,electrode d: V4=VH, and electric potential: V1 (condition 3)): see FIG.18 and FIG. 19 The inclination direction is defined as a firstinclination direction when the plate member 107 a inclines to the sideof the electrode a and the electrode b. In (2-a), (2-b), (2-c), and(2-d), V1=0V, and the electric potential difference between the platemember 107 a and two electrodes to which the plate member 107 a inclinesis greater than VH. Accordingly, the electrostatic force works, and theinclination direction is maintained.

The inclination direction is defined as a second inclination directionwhen the plate member 107 a inclines at the side of the electrode c andthe electrode d and when the plate member 107 a inclines at the side ofthe electrode b and the electrode d.

(2-a) the plate member 107 a inclines in the first inclinationdirection. The electric potentials of the electrode a and the electrodeb are V3=E, and F1 is greater. The electric potential difference betweenthe electric potentials V4=V2=VH of the electrode c and the electrode dand the electric potential V1 of the plate member 107 a is VH. The platemember 107 a is distanced from the electrode c and the electrode d, andF2 is smaller. Accordingly, since F1>F2, the plate member 107 amaintains inclining in the first inclination direction.

(2-b) the electric potential difference between the plate member 107 aand the electric potential V3=E of the electrode a and the electrode bis E, but the plate member 107 a is distanced from the electrode a andthe electrode b and F1 is smaller. The electrostatic force F2 works dueto the electric potential difference VH between the electric potentialV1 of the plate member 107 a and the electric potential V4=V2=VH of theelectrode c and the electrode d. Since F1<F2, the plate member 107 amaintains inclining in the second inclination direction.

(2-c) the electric potential of the electrode a is V3=E, but the platemember 107 a is distanced from the electrode a and F1 is smaller. Theelectric potential difference between the electric potential V1 of theplate member 107 a and the electric potential V4=V2=VH of the electroded is VH, and the electrostatic force F2 works. Since F1<F2, the platemember 107 a maintains inclining in the second inclination direction.

(2-d) the electric potential of the electrode b is V3=E, but the platemember 107 a is distanced from the electrode b, and F1 is smaller. Theelectric potential difference between the electric potential V1 of theplate member 107 a and the electric potential V4=V2=VH of the electrodec is VH, and the electrostatic force F2 works. Since F1<F2, the platemember 107 a maintains inclining in the second inclination direction.

The electric potential of the plate member 107 a is set to be V2(condition 4).

(2-e) the plate member 107 a inclines in the first inclination directionat the side of the electrode a and the electrode b. The electricpotentials of the electrode a and the electrode b are V3=E, and theelectric potential of the plate member 107 a is V2=VH. Accordingly, theelectric potential difference between the plate member 107 a and theelectrodes and the electrodes b is E−VH, and the electrostatic force F3works. The electric potential difference between the electric potentialV2=VH of the plate member 107 a and the electric potential V4=V2=VH ofthe electrode c and the electrode d is 0V, and F4=0. Since F3>F4, theplate member 107 a maintains inclining in the first inclinationdirection.

(2-f) the inclination direction is defined as the second inclinationdirection when the plate member 107 a inclines to the side of theelectrode c and the electrode d. The electric potentials of theelectrode c and the electrode d is V4. Since the electric potential ofthe plate member 107 a is V2=VH, the electric potential differencebetween the plate member 107 a and the electrode c and the electrode dis 0V, and the electrostatic force F4=0. The electric potentials of theelectrode a and the electrode b are V3, and the electric potentialdifference between the plate member 107 a and the electrode a and theelectrode b is E−VH. The plate member 107 a inclines at the side of theelectrode a and the electrode b due to the electrostatic force F3, andF3>F4.

(2-g) the inclination direction is defined as the second inclinationdirection when the plate member 107 a inclines to the side of theelectrode b and the electrode d. Since the electric potential of theplate member 107 a is V2=VH, the electric potential difference betweenthe plate member 107 a and the electrode b is E−VH, and theelectrostatic force pulling the plate member 107 a to the side of theelectrode b is greater. The electric potential of the electrode d is V4.The electric potential difference between the plate member 107 a and theelectrode d is 0V, and the electrostatic force is F4=0. Accordingly, theplate member 107 a is not pulled toward the electrode. The electricpotential of the electrode a is V3. The electric potential differencebetween the plate member 107 a and the electrode a is E−VH, and theelectrostatic force F3 works, and the plate member 107 a inclines at theside of the electrode a. Therefore, the plate member 107 a inclines tothe side of the electrode a and the electrode b, and F3>F4.

(2-h) the inclination direction is defined as the second inclinationdirection when the plate member 107 a inclines at the side of theelectrode a and the electrode c. Since the electric potential of theplate member 107 a is V2=VH, the electric potential difference betweenthe plate member 107 a and the electrode a is E−VH and the electrostaticforce pulling the plate member 107 a to the side of the electrode a isgreater. The electric potential of the electrode c is V4. The electricpotential difference between the plate member 107 a and the electrode cis V, the electrostatic force if F4=0, and the plate member 107 a is notpulled toward the electrode c. The electric potential of the electrode bis V3. The electric potential difference between the plate member 107 aand the electrode b is E−VH, the electrostatic force F3, and the platemember 107 a inclines at the side of the electrode b. Therefore, theplate member 107 a inclines at the side of the electrode a, and theelectrode b, and F3>F4.

State 3 (the first axis and the second axis are selected by combiningthe electrode a, the electrode b, the electrode a, and the electrode d):see FIG. 20, FIG. 21, FIG. 22, and FIG. 23.

Each case of the first axis and the second axis will be described.

The inclination direction is defined as the second inclination directionwhen the plate member 107 a inclines to the side of the electrode c andthe electrode d.

The inclination direction is defined as the first inclination directionwhen the plate member 107 a inclines to the side of the electrode a andthe electrode b or the side of the electrode a and the electrode c.

Condition 2: V1=V5

Condition 3:

(3-1-a) the inclination direction is defined as the first inclinationdirection when the plate member 107 a inclines to the side of theelectrode a and the electrode b. Since the electric potential of theplate member 107 a is V1=0V, the electric potential difference is 0Vbetween the electric potential V1 of the plate member 107 a and theelectric potential V5 of the electrode a and the electrode b, and theelectrostatic force is F5=0. The electric potential of the plate member107 a is V1=0V, the electrostatic force F6 works at the side of theelectrode c and the electrode d which are V6=E. Therefore, the platemember 107 a inclines to the side of the electrode c and the electroded, and F5<F6.

(3-1-b) the plate member 107 a inclines in the second inclinationdirection at the side of the electrode c and the electrode d. Theelectric potential difference is 0V between the electric potential V1 ofthe plate member 107 a and the electric potential V5 of the electrode aand the electrode b, and the electrostatic force F5=0. Since theelectric potential of the plate member 107 a is V1=0V, the electricpotential difference between the plate member 107 a and the electricpotential V6 of the electrode c and the electrode d, and the platemember 107 a maintains inclining to the side of the electrode c and theelectrode d due to a greater electrostatic force. Therefore, F5<F6 whenthe plate member inclines in the second inclination direction.

(3-1-c) the inclination direction is defined as the first inclinationdirection when the plate member 107 a inclines at the side of theelectrode b and the electrode d. Since the electric potential of theplate member 107 a is V1=0V, the electric potential difference is Ebetween the electric potential V6 of the electrode d and the electricpotential V1 of the plate member 107 a, and the electrostatic powerpulling the plate member 107 a to the side of the electrode d isgreater. The electric potential difference is 0V between the electricpotential V5 of the electrode b and the electric potential V1 of theplate member, and F5 is 0 (zero). Accordingly, the plate member 107 a isdisplaced away from the electrode b. The electric potential differenceis E between the electric potential V4 of the electrode c and theelectric potential V1 of the plate member 107 a, the electrostatic forceF6 works, and the plate member 107 a inclines to the side of theelectrode c. Accordingly, the plate member 107 a inclines at the side ofthe electrode c and the electrode d, and F5<F6.

(3-1-d) the inclination direction is defined as the first inclinationdirection when the plate member 107 a inclines to the side of theelectrode a and the electrode c. Since the electric potential V1 of theplate member 107 a is 0V, the electric potential difference is E betweenthe electric potential V5 of the electrode c and the electric potentialV1 of the plate member 107 a, and the electrostatic power pulling theplate member 107 a to the side of the electrode c is greater. Theelectric potential difference is 0V between the electric potential V5 ofthe electrode a and the electric potential V1 of the plate member 107 a,V5 is 0 (zero), and the plate member 107 a is displaced away from theelectrode a. The electric potential difference is E between the electricpotential V6 of the electrode d and the electric potential V1 of theplate member, the electrostatic force F6 works, and the plate member 107a inclines to the side of the electrode d. Accordingly, the plate member107 a inclines to the side of the electrode c and the electrode d, andF5<F6.

Condition 4:

In (3-1-e), (3-1-f), (3-1-g), and (3-1-h), the electric potential V2 ofthe plate member is VH (V2=VH), the electric potential difference isgreater than VH between two electrodes at the side where the platemember 107 a inclines, and the plate member 107 a, and the electrostaticforce works in the inclination direction. Accordingly, the inclinationdirection is maintained.

When the plate member 107 a inclines to the side of the electrode a andthe electrode b, or when the plate member 107 a inclines to the side ofthe electrode a and the electrode c, the inclination direction isdefined as the first inclination direction.

(3-1-e) the electric potentials V5 of the electrode a and the electrodeb are 0V, electric potential difference is VH between the electricpotentials V5 of the electrode a and the electrode b and the electricpotential V2 of the plate member 107 a, and the electrostatic force F7works. The electric potentials V6 of the electrode c and the electrode dare E (V6=E), the electric potential difference is VH between theelectric potentials V6 of the electrode c and the electrode d and theelectric potential V2 of the plate member 107 a, and the electrostaticforce F8 works. The plate member 107 a is distanced from the electrode band the electrode d, and the electrostatic force F8 is smaller.Accordingly, F7>F8, and the plate member 107 a maintains inclining inthe first inclination direction.

(3-1-f) the plate member 107 a inclines in the second inclinationdirection at the side of the electrode c and the electrode. The electricpotential difference is VH between the electric potentials V5 of theelectrode a and the electrode b and the electric potential V2 of theplate member 107 a, the plate member 107 a is distanced from theelectrode a and the electrode b, and the electrostatic force F7 issmaller. The electric potential V6 of the electrode c and the electroded is E (V6=E), the plate member 107 a is closer to the side of theelectrode c and the electrode d, and the electrostatic force F8 isgreater. The plate member 107 a maintains inclining in the secondinclination direction at the side of the electrode c and the electroded. When the plate member 107 a inclines in the second inclinationdirection, F7<F8.

(3-1-g) the electric potential V5 of the electrode b is 0V, the electricpotential difference is VH between the electric potential V5 of theelectrode b and the plate member 107 a of the electric potential V2, andthe electrostatic force F7 works. The electric potential V6 of theelectrode c is E (V6=E), the electric potential difference is VH betweenthe electric potential V6 of the electrode c and the electric potentialV2 of the plate member 107 a, and the electrostatic force F8 works. Theplate member is distanced from the electrode c, and the electrostaticforce F8 is smaller. Accordingly, F7>F8, and the plate member 107 amaintains inclining in the second inclination direction.

(3-1-h) the electric potential V5 of the electrode a is 0V, the electricpotential difference is VH between the electric potential V5 of theelectrode a and the electric potential V2 of the plate member 107 a, andthe electrostatic force F7 works. The electric potential V6 of theelectrode d is E (V6=E), the electric potential difference is VH betweenthe electric potential V6 of the electrode d and the electric potentialV2 of the plate member 107 a, and the electrostatic force F8 works. Theplate member 107 a is distanced from the electrode d, and theelectrostatic force F8 is smaller. Accordingly, F7>F8, and the platemember 107 a maintains inclining in the first inclination direction.

State 3: second axis (electrode a: 0V, electrode b: E, electrode c: 0V,electrode d: E)

Condition 3: the inclination direction is defined as the secondinclination direction when the plate member 107 a inclines at the sideof the electrode b and the electrode d.

(3-2-a) the plate member 107 a inclines at the side of the electrode aand the electrode b, and the inclination direction is defined as thefirst inclination direction. The electric potential V1 of the platemember 107 a is 0V (V1=0V), the electric potential difference is Ebetween the electrode b and the plate member1 107 a, and theelectrostatic force pulling the plate member 107 a to the side b isgreater. The electric potential difference is 0V between the electricpotential V5 of the electrode a and the electric potential V1 of theplate member 107 a, the electrostatic force F5 is 0 (F5=0), and theplate member 107 a is displaced away from the electrode a. The electricpotential difference is E between the electric potential V6 of theelectrode d and the electric potential V1 of the plate member 107 a, theelectrostatic force F6 works, the plate member 107 a inclines at theside of the electrode d. Accordingly, the plate member 107 a inclines atthe side of the electrode b and the electrode d, and F5<F6.

(3-2-b) the plate member 107 a inclines at the side of the electrode cand the electrode d, and the inclination direction is defined as thesecond inclination direction. Since the electric potential V1 of theplate member 107 a is 0V (V1=0V), the electric potential difference is Ebetween the electrode d and the plate member 107 a, and theelectrostatic force pulling the plate member 107 a to the side of theelectrode d is greater. The electric potential difference is 0V betweenthe electric potential V5 of the electrode c and the electrode V1 of theplate member 107 a, the electrostatic force F5 is 0 (F5=0), the platemember 107 a is displaced away from the electrode c. The electricpotential difference is E between the electric potential V6 of theelectrode b and the electric potential V1 of the plate member 107 a, theelectrostatic force F6 works, the plate member 107 a inclines at theside of the electrode b. Accordingly, the plate member 107 a inclines atthe side of the electrode b and the electrode d, and F5<F6.

(3-2-c) the plate member 107 a inclines at the side of the electrode aand the electrode c, and the inclination direction is defined as thefirst inclination direction. The electric potential V1 of the platemember 107 a is 0V (V1=0V), the electric potential difference is 0Vbetween the electric potential V1 of the plate member and the electricpotential V6 of the electrode c, and the electrostatic force F5 is 0(F5=0). The electric potential difference is E between the electricpotentials V6 (=E) of the electrode b and the electrode d and theelectric potential V1 of the plate member 107 a, and the plate member107 a inclines at the side of the electrode b and the electrode d due tothe electrostatic force F6.

(3-2-d) the plate member 107 a inclines the side of the electrode b andthe electrode d, and the inclination direction is defined as the secondinclination direction. The electric potential V1 of the plate member 107a is 0V (V1=0V), the electric potential difference is 0V between theelectric potentials V5 (=0V) of the electrode a and the electrode c, andthe electrostatic force F5 is 0 (F5=0). The electric potentialdifference is E between the electric potentials V4 (=E) of the electrodeb and the electrode d and the electric potential V1 of the plate member107 a. Accordingly, the plate member 107 a maintains inclining at theside of the electrode b and the electrode d due to the electrostaticforce F6, and F5<F6.

Condition 4:

In (3-2-e), (3-2-f), (3-2-g), and (3-2-h), the electric potential V2 ofthe plate member 107 a is VH (V2=VH), and the electric potentialdifference is more than VH between the side of two electrodes at whichthe plate member 107 a inclines, and the plate member 107 a.Accordingly, the electrostatic force works and the inclination directionis maintained. The inclination direction is defined as the firstinclination direction when the plate member 107 a inclines at the sideof the electrode a and the electrode b. The inclination direction isdefined as the second inclination direction when the plate member 107 ainclines at the side of the electrode c and the electrode d or when theplate member 107 a inclines at the side of the electrode b and theelectrode d.

(3-2-e) the electric potential V5 of the electrode a is 0V (V5=0V), theelectric potential difference is VH between the electric potential V5 ofthe electrode a and the electric potential V2 of the plate member 107 a,and the electrostatic force F7 works. The electric potential differenceis E−VH between the electric potential V6 (=E) of the electrode d andthe electric potential V2 of the plate member 107 a, the electrostaticforce F8 works. The plate member 107 a is distanced from the electroded, and the electrostatic force F8 is smaller. Accordingly, F7>F8, andthe plate member 107 a maintains inclining in the first inclinationdirection.

(3-2-f) the electric potential V5 of the electrode c is 0V, the electricpotential difference is VH between the electric potential V5 of theelectrode c and the electric potential V2 of the plate member 107 a, andthe electrostatic force F7 works. The electric potential difference isE−VH between the electric potential V6 (=E) of the electrode b and theelectric potential V2 of the plate member 107 a, and the electrostaticforce F8 works. The plate member 107 a is distance from the electrode d,and the electrostatic force F8 is smaller. Accordingly, F7>F8, and theplate member 107 a maintains inclining in the second inclinationdirection.

(3-2-g) the plate member 107 a inclines in the second inclinationdirection at the side of the electrode b and the electrode d. Theelectric potential difference is VH between the electric potentials V5of the electrode a and the electrode c and the electric potential V2 ofthe plate member 107 a, the plate member 107 a is distanced from theelectrode a and the electrode c, and the electrostatic force F7 issmaller. The electric potentials V6 (=E) of the electrode b and theelectrode d, the plate member 107 a is closer to the side of theelectrode b and the electrode d, and the electrostatic force F8 isgreater. The plate member 107 a maintains inclining in the secondinclination direction at the side of the electrode b and the electroded. When the plate member 107 a inclines in the second inclinationdirection, F7<F8.

(3-2-h) the electric potential V5 of the electrode a and the electrode cis 0V, the electric potential difference is VH between the electricpotential V5 of the electrode a and the electrode c and the electricpotential V2 of the plate member 107 a, the electrostatic force F7works. The electric potential difference is VH between the electricpotentials V6 of the electrode b and the electrode d is E (V6=E) and theelectric potential V2 of the plate member 107 a, and the electrostaticforce F8 works. The plate member 107 a is distanced from the electrode band the electrode d, and the electrostatic force F8 is smaller.Accordingly, F7>F8, and the plate member 107 a maintains inclining inthe first direction.

As described above, in the state 1, regardless of the electric potential0V or VH of the plate member 107 a, the inclination direction of theplate member 107 a is maintained. Accordingly, if data are written inthis state, the inclination direction is not changed. In the state 2,the electric potential of the plate member 107 a is VH, and theinclination direction of the plate member 107 a changes to the side ofthe electrode a and the electrode b, and returns. In the state 3, theelectric potential of the plate member 107 a is 0V, and the inclinationdirection of the plate member 107 a is changed to the side of theelectrode c and the electrode d by an electric potential for the firstaxis or to the side of the electrode b and the electrode d by anelectric potential for the second axis.

FIG. 24 is a diagram showing a timing chart. From an upper row, a changeof the electric potential of the electrode a in a time sequence, achange of the electric potential of the electrode b in the timesequence, a change of the electric potential applying to the platemember 107 a by the fulcrum member 106, a change of the electricpotential of the electrode c in the time sequence, and a change of theelectric potential of the electrode c in the time sequence are shown.

A state transition in an order of the state 1, the state 2, the state,3, and the state 1 will be described. When the plate member 107 ainclines at the side of the electrode a and the electrode c, light isOFF. When the plate member 107 a inclines at the side of the electrode cand the electrode d, the light is ON by a first axis. When the memberplate 107 a inclines at the side of the electrode b and the electrode d,the light is ON by a second axis.

A lateral axis shows the time sequence. A longitudinal axis shows theelectric potential. In FIG. 24, a case of a display by the second axisafter the display by the first axis is shown. However, the first axis orthe second axis can be arbitrarily selected. Alternatively, the statetransition can be conducted in an order of the state 1, the state 3, thestate 2, and the state 1.

In the state 1, an image is displayed. Simultaneously, data fordisplaying in a next state 1 are prepared in a memory connected to thefulcrum member 106, and the electric potential 0V or VH is applied tothe plate member 107 a in accordance with image information.

In the state 2, since the electric potential of the plate member 107 ais VH, the plate member 107 a inclines at the side of the electrode aand the electrode b or maintains inclining in the inclination directionat this point.

In the state 3, if the electric potential of the plate member 107 a is0V, the plate member 107 a inclines at the side of the electrode c andthe electrode d or the side of the electrode b and the electrode d inaccordance with the first axis or the second axis. As shown in FIG. 20,FIG. 21, FIG. 22, and FIG. 23, an indication of the first axis or thesecond axis can be switched by combining the electrode a, the electrodeb, the electrode c, and the electrode d. If the electric potential ofthe plate member 107 a is VH, the inclination direction in the state 2is maintained. Data are written and an image is displayed in the state 1(the inclination direction is maintained), the plate member 107 ainclines to the OFF side in the state 2, and the inclination directionof the plate member 107 a is changed by the data, that is, the image isdisplayed in the state 3. Next, the inclination direction of the platemember 107 a is maintained and the image is displayed in the state 1.During the state 1, next data are supplied from the memory. However, theinclination direction of the plate member 107 a is not changed.

As described above, a series of flow is formed. For a minimum displaytime, 32 μsec. is set for the state 1. In the optical deflecting device,since a rising time is approximately 3 μsec., 3 μsec. is set for thestate 2 and the state 3, respectively.

Third Embodiment

In a case in that a plurality of an optical deflecting devices areformed in one dimension or in two dimensions, electrodes among theplurality of optical deflecting devices forming pixels, for example,every electrode a is connected among the plurality of optical deflectingdevices, and every electrode b, every electrode c, and every electrode dare connected similarly among the plurality of optical deflectingdevices. In particular, in a case of connecting the electrodes of theoptical deflecting device array in the two dimensions for each of fourtypes, four power sources are used.

FIG. 25 is a diagram showing an example of a region division. In FIG.25, a line represents a wire. For example, at each intersection point oflines from a column driver and lines from a row driver, a semiconductormemory device such as an SRAM (Static Random Access Memory) is arranged.On an upper layer, the optical deflecting device according to thepresent invention including a electrode group and a plate member 107 ais formed. As shown in FIG. 25, a region pointed by an address isdivided, so as to switch outputs of light of the first axis and light ofthe second axis.

In the third embodiment, a case of dividing the region into four regionsis illustrated as a region 1, a region 2, the region 3, and a region 4.The electrode a, the electrode b, the electrode c, and the electrode dare connected, respectively, in the region 1, the region 2, the region3, and the region 4. A driving power source is arranged with respect toeach of the region 1, the region 2, the region 3, and the region 4.Sixteen power sources cover the entire for a total of four regions. Asdescribed above, the optical deflection can be conducted by switching anaxis for each of the four regions.

Fourth Embodiment

FIG. 26 is a diagram showing a configuration of a projection apparatus1101 using an optical deflecting device 1001 according to the presentinvention and applying a method for driving the optical deflectingdevice 1001. Light having a certain wider angle from a light source 1102is illuminated to the optical deflecting device 1001, for example,through a rotation color filter 1105. Reflected light from thereflection area of the plate member 107 a is illuminated on a projectionscreen 1110 through a projection lens 1106 in a case of a firstinclination direction of the plate member 107 a. This state is an ONstate. On the other hand, in a case of a second inclination direction,reflected light is blocked by a light shielding member 1104 as anaperture and does not output light to the projection screen 1110. Thisstate is an OFF state.

In a case in that the plurality of the optical deflecting devices arearranged in the two dimensional array, by the ON state and the OFFstate, it is possible to form an image on the projection screen 1110.The optical deflecting device 1001 can be used as an optical switchmeans of a display apparatus (that is, an apparatus for a contrastdisplay of a pixel) for image projection data. Accordingly, a contrastcontrol of a pixel (that is, ON/OFF control of an optical switch)becomes preferable, stray light (reflected light from an adjacent pixeloccurred when the reflection direction is displaced) can be controlled,an operation can be conducted at higher speed, higher reliability can berealized in a long-term, a lower voltage can drive the opticaldeflecting device, and a contrast ratio can be improved.

Fifth Embodiment

FIG. 27 is a diagram showing a configuration of a projection apparatususing a two-axis optical deflecting device. The two-axis opticaldeflecting device 1201 and a one-axis optical deflecting device 1101 areused. Light from a light source 1202 is illuminated to the two-axisoptical deflecting device 1201 and the optical deflecting device 1101 asincoming light C1, C2, and C3 by an optical system 1203 configured by amirror, a lens and a like.

As described in FIG. 15 and FIG. 16, angles of the incoming light C1,C2, and C3 reflected at a plate member being inclined are defined sothat the incoming light C1, C2, and C3 are perpendicularly reflectedwith respect to a substrate of the optical deflecting device. Inparticular, the incoming light C1 and C2 are set to be different by 90°in a plane surface of the substrate of the two-axis optical deflectingdevice 1201. The incoming light C1 is an incoming light flux of anarbitrary color, light C1 (ON) is a reflected light flux (hereinafter,called an ON light) being led to a projection lens 1205 when the ONoperation is conducted for the arbitrary color, and light C1 (OFF) is areflected light flux (hereinafter, called an OFF light) being led to alight absorption plate 1204 displaced away from the projection lens 1205when the OFF operation is conducted. The incoming light C2 is anincoming light flux of an arbitrary color different from the arbitrarycolor of the incoming light C1, light C2 (ON) is the ON light of thearbitrary color, and light C2 (OFF) is the OFF light of the arbitrarycolor. The incoming light C3 is an incoming light flux of an arbitrarycolor different from the arbitrary colors of the incoming light C1 andthe incoming light C2, light C3 (ON) is the ON light of the arbitrarycolor, and light C3 (OFF) is the OFF light of the arbitrary color. Forexample, each of the incoming light C1, C2, and C3 is one of threeprimary colors (red, green, and blue), or is a color having a differentwavelength. Each of the incoming light C1, C2, and C3 is shown by ablack arrow. In practice, each of the incoming light C1, C2, and C3 is alight beam having a width possible to illuminate the entire surface ofan optical deflecting device array.

For example, the light source 1202 is a white color light source such asa xenon lamp, a halogen lamp, a mercury lamp, or a like. The opticalsystem 1203 combining the optical lens and the mirror is illustrativelyshown by waved lines in order to avoid an intricate drawing. As acombination, for example, the optical system 1203 may include an IR cutmirror or an IR cut filter for cutting infrared light, an integratorlens or a rod lens for changing light from the light source 1202 toparallel light, a dichroic mirror or a dichroic prism for separating atarget color from the white color source, and a total reflection mirroror a TIR prism for changing an illumination direction for each color toilluminate the optical deflecting device array. The optical system 1203mainly separates light L from the light source 1202 into the incominglight fluxes C1 and C2 of arbitrary colors, and changes directions ofthe incoming light fluxes C1 and C2 to illuminate the optical deflectingdevice array. Thus, the above-described combination can easily achievean purpose of the optical system 1203.

It is possible to combine three-different colors by combining the lightC1 (ON), the light C2 (ON), and the light C3 (ON) by the colorcombination prism 1212. Therefore, it is possible to display an image ona screen 1210 with high color tone through the projection lens 1205.

The following advantages can be considered by applying the two-axisoptical deflecting device to a projection apparatus. That is, in a caseof using an one-axis optical deflecting device of a single plate type, aswitch time of the one-axis optical deflecting device is assigned foreach color in a time sharing by using a color wheel. In thisconfiguration, there is a problem called a color break in that a colordisturbance occurs in a rapid motion picture.

On the other hand, in the method for driving the optical deflectingdevice array according to the present invention, two types of light canbe deflected by a two-axis operation. For example, a color switch can berealized for the entire surface of the two-axis optical deflectingdevice array, ½ screen, or ¼ screen, and each color can be evenly mixed.Therefore, it is possible to significantly suppress the color break.

For example, in an image projection apparatus using a plurality ofdeflecting devices arranged in an array, in a case of an opticaldeflecting device including a plate member having a torsion beam, it isdifficult to minimize the torsion beam and then, it is difficult tominimize the pixels in order to refine precision of a pixel. On theother hand, it is easy to minimize the optical deflecting device in aconfiguration using a plate member without having a fixed portion. Inthe method for driving the optical deflecting device array, it ispossible to control a drive of the plate member without the fixedportion by an operation voltage of a semiconductor memory device such asan LSI which is typical and is highly integrated, and it is possible toeasily minimize the plate member in order to improve the precision. Inaddition, it is possible to use a higher driving voltage to realize anoperation of the plate member at higher speed.

In particular, in a case of conducting a gradation display during the ONlight or the OFF light by switching light emitted from the light sourceby using the reflection area of the plate member, when pixel data issent to the semiconductor memory device for storing display data of theoptical deflecting device within a minimum display period, the opticaldeflecting device forming a pixel in an array simultaneously switcheslight. Therefore, the minimum display period cannot be influenced by aswitch time.

In the present invention, in a case of arranging a plurality of theoptical deflecting device in an one dimension or in a two dimensions,electrodes of the same type and the same position are wired in commonfor the optical deflecting devices, so that only the number of powersources corresponding to the number of types of the electrodes cansupply power entirely, and the number of power sources can be reduced.In addition, it is possible to switch an axis direction for each region,and it is possible to switch a color if a light color is differentbetween a first axis and a second axis.

In the present invention, by forming the optical deflecting device on oradjacent to the semiconductor memory device, it is possible to shortenthe wires, there is no interference among a plurality of the opticaldeflecting devices, and it is possible to reduce the number of wiringlines. In addition, it is possible to record image data to thesemiconductor memory device, and to simultaneously deflect light by theplurality of the optical deflecting devices in the array. Therefore, adeflection switch time does not influence the display time length.

In the present invention, by using an SRAM as the semiconductor memorydevice, it is possible to certainly record the image data. In addition,it is possible to reduce the number of transistors in a configuration ofthe semiconductor memory device. Therefore, it is possible to easilyminimize a pixel without increasing a range of the plate member.

In the present invention, a distance between the plate member and anelectrode group to which the plate member is close becomes even closer,and the electrostatic force becomes even stronger per electric potentialdifference. Therefore, it is possible to maintain the distance betweenthe plate member and the electrode group even if a voltage is lower, andit is possible to reduce a control voltage of the plate member.Alternatively, it is possible to make the driving voltage of the platemember to be higher.

In the present invention, it is possible to change to one of fourinclination directions by approximately 90° in a plain surface of thesubstrate by switching electric potentials of four electrodessurrounding the fulcrum member. Accordingly, it is possible to switchthe two-axis direction of light. By this configuration, for example, ina case of applying the present invention to an image projectiondisplaying apparatus, it is possible to individually change theinclination direction with respect to a plurality of regions forming adisplay area of a plurality of colors. Therefore, it is possible tosmoothly change a color display.

In the present invention, electric potentials of two electrodes in therotation axis of the plate member and a parallel direction are set to bethe same. Therefore, it is possible to stably rotate since anelectrostatic force between both two electrodes and the plate memberbecomes the same.

According to the present invention, the contrast control of the pixelcan be preferable by the ON/OFF control of the optical deflectingdevice, the operation can be conducted at higher speed, higherreliability can be realized in a long-term, a lower voltage can drivethe optical deflecting device, and a contrast ratio can be improved.Therefore, it is possible to provide the image projection displayingapparatus with higher precision having a higher contrast ratio withhaving higher brightness.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

The present application is based on the Japanese Priority ApplicationsNo. 2004-320821 filed on Nov. 4, 2004, the entire contents of which arehereby incorporated by reference.

1. A method for driving an optical deflecting device array, which arranges a plurality of optical deflecting devices in one dimension or in two dimensions, each of the plurality of optical deflecting devices in which a plate member having a light reflection area rotates on a rotation axis or a fulcrum being as a center, and a light deflection operation is conducted by changing a reflection direction of an incoming light flux in that the plate member includes a conductive layer, an electrode is contacted or fixed to the conductive layer to apply an electric potential, and each of the plurality of optical deflecting device includes an electrode group including a plurality of electrodes arranged to face to the plate member, and switching an inclination direction of the plate member due to an electrostatic attraction caused by an electric potential difference between an arbitrary electrode in the electrode group and the electrode applying the electric potential to the conductive layer, said method comprising: in a series of processes for the light deflection operation, at least, a state of a first stage writing and recording data for indicating an inclination direction of the plate member to incline in a first inclination direction or a second inclination direction, into a semiconductor memory device arranged immediately under or adjacent to each of the plurality of optical deflecting devices; a state of a second stage switching the inclination direction of the plate member of the arbitrary optical deflecting device to the first inclination direction based on an indication of the data, and deflecting light; and a state of a third stage switching the inclination direction of the plate member of the arbitrary optical deflecting device to the second inclination direction based on the indication of the data, and deflecting light.
 2. The method for driving the optical deflecting device as claimed in claim 1, wherein the state of the first stage is conducted for each of the optical deflecting devices forming the optical deflecting device array at a different time, the state of the second stage and the state of the third stage are conducted at the plurality of the optical deflecting devices at one time.
 3. The method for driving the optical deflecting device array as claimed in claim 1, wherein a switch of the inclination direction in the state of the second stage is conducted by applying an electric potential which satisfies a condition 1, a condition 2, and a condition 3, wherein: the condition 1 is a condition for selecting an electric potential V1 or an electric potential V2 for each of the optical deflecting devices based on data for indicating the inclination direction in which the electric potential V1 or the electric potential V2 is applied to the electrode contacted or fixed to the conductive layer formed to the plate member; the condition 2 is a condition in which an electric potential V3 is applied to at least one electrode arranged at a side of the first inclination direction with respect to the rotation axis or the fulcrum being as the center from the electrode group arranged to face to the plate member, an electric potential V4 approximately equivalent to an electric potential V2 is applied to at least one electrode arranged at a side of the second inclination direction with respect to the rotation axis or the fulcrum being as the center, and the electric potential V3 and the electric potential V4 are applied to the plurality of optical deflecting devices at one time with the same electric potential, the condition 3 is a condition in which an electrostatic attraction F1 occurred due to an electric potential difference between the electric potential V3 of the electrode arranged at the side of the first inclination direction and the electric potential V1 of the conductive layer formed to the plate member has a magnitude relation with an electrostatic attraction F2 occurred due to an electric potential difference between the electric potential V4 of the electrode arranged at the side of the second inclination direction and the electric potential V1 of the electrode arranged at the side of the second inclination direction: F1>F2 when the plate member inclines in the first inclination direction at an initial state; and F1<F2 when the plate member inclines in the second inclination direction at an initial state, and the condition 4 is a condition in which an electrostatic attraction F3 occurred due to an electric potential difference between the electric potential V3 of the electrode arranged at the first inclination direction and the electric potential V2 of the conductive layer formed to the plate member has a magnitude relation with an electrostatic attraction F4 occurred due to an electric potential difference between the electric potential V4 of the electrode arranged at the second inclination direction and the electric potential V2 of the conductive layer formed to the plate member: F3>F4 when the plate member inclines in the first inclination direction at an initial state; and F3>F4 when the plate member inclines in the second inclination direction at the initial state.
 4. The method for driving the optical deflecting device array as claimed in claim 1, wherein a switch of the inclination direction in the state of the third stage is conducted by applying an electric potential which satisfies a condition 1, a condition 2, and a condition 3, wherein: the condition 1 is a condition for selecting the electric potential V1 or the electric potential V2 for each of the optical deflecting devices based on data for indicating the inclination direction in which the electric potential V1 or the electric potential V2 is applied to the electrode contacted or fixed to the conductive layer formed to the plate member; the condition 2 is a condition in which an electric potential V5 approximately equivalent to the electric potential V1 is applied to at least one electrode arranged at a side of the first inclination direction with respect to the rotation axis or the fulcrum being as the center from the electrode group arranged to face to the plate member, an electric potential V6 is applied to at least one electrode arranged to the side of the second inclination direction with respect to the rotation axis or the fulcrum being as the center, and the electric potential V5 and the electric potential V6 are applied to the plurality of optical deflecting devices at one time with the same electric potential, the condition 3 is a condition in which an electrostatic attraction F5 occurred due to an electric potential difference between the electric potential V5 of the electrode arranged at the side of the first inclination direction and the electric potential V1 of the conductive layer formed to the plate member has a magnitude relation with an electrostatic attraction F6 occurred due to an electric potential difference between the electric potential V6 of the electrode arranged at the side of the second inclination direction and the electric potential V1 of the electrode arranged at the side of the second inclination direction: F5<F6 when the plate member inclines in the first inclination direction at the initial state; and F5<F6 when the plate member inclines in the second inclination direction at the initial state, and the condition 4 is a condition in which an electrostatic attraction F7 occurred due to an electric potential difference between the electric potential V5 of the electrode arranged at the first inclination direction and the electric potential V2 of the conductive layer formed to the plate member has a magnitude relation with an electrostatic attraction F7 occurred due to an electric potential difference between the electric potential V6 of the electrode arranged at the second inclination direction and the electric potential V2 of the conductive layer formed to the plate member: F7>F8 when the plate member inclines in the first inclination direction at the initial state; and F7>F8 when the plate member inclines in the second inclination direction at the initial state. 